The meager is an emblematic migratory fish of this area of the Atlantic coast, which goes from Gironde to Charente-Maritime.
To collect different data on the paths of this species, the Marine Nature Park has equipped around twenty fish with beacons which will rise to the surface in twelve months.
The objective is to know the level of exploitation of this species, and whether it is sustainable or not.
In France, lean is fished throughout the Bay of Biscay.
But 80% of the population is exploited in the area of the Marine Natural Park of the Gironde estuary and the Pertuis sea.
As such, this makes it an "emblematic" migratory fish of this area of the Atlantic coast, which goes from Gironde to Charente-Maritime.
However, this species remains unknown.
This is why the Marine Nature Park has just equipped twenty skinny adults with beacons, after the reproduction phase, which takes place in June in the Gironde estuary.
They will make it possible to collect various data on their journeys, in the Marine Park sector and beyond.
After twelve months, the beacons will detach and rise to the surface to transmit data via the Argos satellite network.
Between 600 and 800 tonnes caught per year
The tagging of the fish will thus be used to identify the area of distribution of these meager.
“We are going to follow the movements of the twenty tagged fish for a year, to understand if the population of lean fish in the park is the same as that exploited in Portugal, or if they are subservient to the park, explains Yohan Weiller, fishing project manager and shellfish farming in the Marine Nature Park.
It is a central question, to know if it is necessary to set up a management at the French level, or with the Spaniards and the Portuguese.
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"We need to know more about the level of lean exploitation, and above all whether it is sustainable or not," continues Yohan Weiller.
For this we need a lot of information, especially on the history, the size and the places of capture.
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Such information already exists for a number of species fished on the Atlantic coast, but not for meager.
“The meager being a relatively unknown species, there is little sharing of information.
We can only measure the landing levels [by fishermen], which have remained relatively stable for the past fifteen years, between 600 and 800 tonnes per year.
For example, landings of sole in the Bay of Biscay are around 3,700 tonnes per year, even if the scale of the stock is not the same.
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The objective is to define levels of exploitation
Led by Ifremer, this initiative, which falls within the framework of the Acost project (Improving knowledge of stocks in the Bay of Biscay), is carried out in collaboration with fishermen.
“For the markings, we asked a professional to board his boat, and the fishermen are the first to need to know what the level of exploitation of such and such a species is, assures the project manager.
The objective of the Acost project, which runs until 2025, is to define operating levels, but that will come later.
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Lean is a “very special” fish, recalls Yohan Weiller.
It frequents areas off Mauritania, southern Portugal, northern Egypt and in the Bay of Biscay.
In spring, the adults go up along the coasts of the Landes to move towards the estuary of the Gironde, their only known breeding area in France.
It is also a fish that has the particularity “of being able to grow very quickly, and enormously, to reach up to 60 kg and two meters in length.
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Created in 2015, the Marine Park has, among other objectives, the protection of coastal ecosystems.
“Estuaries and coastal areas are generally nursery areas for small fish resulting from reproduction, explains Yohan Weiller.
As such, these areas are therefore essential for the reproduction of fish.
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